The present invention relates to printed wiring boards for use in general electronic appliances in the home or office.
Previously, environments excessively inhabited by insects were not appreciated, and no measures were taken against the invasion or nesting of insects in electronic appliances. Without any particular internal measures against insects, only the shape of housing of the electronic appliances was designed to prevent invasion, and further measures to rid the entire external environments were considered.
However, the downsizing of electronic appliances, diversified needs for saving energy, increases in the number of electronic household appliances (rice cooker, refrigerator, microwave oven, etc.), and growth of dining industry, has created a mounting demand for reliable electronic appliances for professional kitchens, restaurants and others (air conditioner, security system, electronic cooking apparatus, business telephone, etc.). Hence, insect countermeasures are required inside the electronic appliances.
Presently, electronic materials containing repellents, are manufactured by mixing repellent directly into the resin. However, the manufacturing method of electronic materials containing repellents requires mixing large amounts of repellent in the resin, and blurring was likely to occur when applying or forming. Furthermore, there are problems in stability of quality. Moreover, the conventional manufacturing method of electronic materials containing repellents requires higher ultraviolet exposure, greater temperatures, and longer time, by 50 to 100%, as compared with other general ultraviolet curing solder resist, thermosetting solder resist, or parts layout. Consequently, the repellent effect was lowered during the curing process.
Moreover, in order to apply and form the electronic materials containing repellents in the entire region except for the soldering lands or the like, it is difficult to establish the manufacturing conditions such as printing conditions (plate gap, printing speed, etc.) and curing condition (curing method, temperature, time, etc.). Accordingly, the repellent effect and quality were unstable. When the electronic materials containing repellents are applied and formed in the entire region except for the soldering lands or the like, fluctuations of thickness of the formed film and warping of printed wiring board are likely to occur. As a result, when mounting parts on the surface, defective printing of solder paste, defective standing of chips, and deviation of position of mounted parts were experienced.
In the conventional electronic materials containing repellents, since it was necessary to mix a large amount of repellents in the resin, blurring was likely to occur when the electronic materials were applied and formed, and it was difficult to assure the quality. Moreover, since the higher ultraviolet exposure and temperature and longer time by 50 to 100% than usual were needed, the repellents disappeared gradually, and the repellent effect was lowered. Besides, as the electronic materials containing repellents were applied and formed in the entire region except for the soldering lands or the like, the plate gap increased, the printing speed dropped, and the printing conditions were worsened. As a result, blurring and deviation occur and the quality is unstable. Moreover, due to worsening of curing conditions such as higher temperature and longer time, the repellents are gradually lost and the repellent effect is lowered.
Still worse, as the electronic materials containing repellents are applied and formed in the entire region except for the soldering lands or the like, fluctuations of thickness of the formed film and warping of printed wiring board are likely to occur. As a result, when mounting small-sized parts on the printed board, defective printing of solder paste, defective standing of chips, and deviation of position of mounted parts are likely to occur.
Hence it is an object of the invention to improve the quality of printed wiring board (deviation in thickness, blurring, warping, etc.), enhance the repellent effect efficiently, and maintain stability, while presenting a printed wiring board with insect countermeasures and its manufacturing method capable of decreasing warp and other defects in the mounting process of components.
A printed wiring board of the invention comprises:
an insulating substrate having first and second surfaces,
conductive and insulting layers on at least one of the first and second surfaces, and
an electronic material formed on at least one of the first surface and second surface of the insulating substrate having the conductive layer and insulating layer,
in which the electronic material contains a repellent having an insect repelling performance and a binder, and the electronic material is formed with a selective pattern.
A manufacturing method of a printed wiring board of the invention comprises:
(a) a step of placing a conductive layer in at least one of a first surface and a second surface of an insulating substrate,
(b) a step of placing an insulating layer so as to cover the conductive layer, and
(c) a step of forming an electronic material containing a repellent having an insect repelling performance and a binder, on at least one of the first surface and the_@ second surface, with a selective pattern.
This constitution suppresses invasion and occupation of insects having sensory nerves such as cockroaches and ants in the printed wiring board. It prevents troubles of electronic appliances due to dead bodies or wastes of these insects. As a result, the reliability of electronic appliances is enhanced. It further prevents thickness fluctuation or blurring of the repellent layer of the electronic material mixing the repellent. The printed wiring board of the invention is free from warp or other abnormal appearance. By using the printed wiring board of the invention, occurrence of defects is decreased in the process of mounting the parts. Further, the productivity is enhanced. The printing wiring board having all these effects is obtained. Thus, without sacrificing the repellent effect, the productivity is enhanced, the quality is improved, and the cost is reduced.